A kind of polyester resin for high-gloss powder coating and its preparation method and application

Abstract

The invention belongs to the technical field of powder coatings, in particular to polyester resin for a high gloss powder coating and a preparation method thereof and application thereof in preparinga 50 / 50 type powder coating. The polyester resin for the high gloss powder coating is prepared by polymerization of octadecanedioic acid, isophthalic acid, 4-trifluoromethylsalicylic acid, 2,6-Bis(hydroxymethyl)-p-cresol, neopentyl glycol, glyceryl isostearate, 1,6-hexanediol dimethacrylate, and 2,3-quinolinedicarboxylic acid as raw materials. The obtained polyester resin product has better structural flexibility and long flow time, has high surface gloss after curing into a film while ensuring mechanical properties, and can be used in the 50 / 50 mixed powder coating for obtaining a high glosscoating board surface.

Description

technical field [0001] The invention belongs to the technical field of powder coatings, specifically relates to a polyester resin for high-gloss powder coatings, and further discloses its preparation method and its application for preparing 50 / 50 mixed powder coatings. Background technique [0002] Powder coating is a 100% solid powder that does not contain organic solvents. It is different from oil-based paints and water-based paints. It does not use solvent or water as a dispersion medium when coating, but uses air as a dispersion medium to evenly coat the workpiece. The surface is a new type of environmentally friendly paint that forms a special-purpose coating film after heating. Powder coating has the advantages of no VOC, environmental protection, energy saving, high construction efficiency and wide application range. With its advantages of economy, environmental protection, high efficiency and excellent performance, it is gradually replacing organic solvent-based coat...

AI Technical Summary

Problems solved by technology

In order to obtain high leveling performance, it is required that the viscosity of polyester resin as the key material of powder coating should be low, but the viscosity is too low to affect the mechanical properties of the resin; on the other hand, in order to have qualified storage stability, polyester resin for powder coating is required The glass transition temperature of the resin must be above 50°C, and the weather-resistant polyester must even reach above 60°C. However, if the glass transition temperature is too high, the melt flow temperature of the resin will also increase accordingly, which will affect its leveling property and cause it to deteriorate. affect the gloss properties

[0005] In addition, for the 50 / 50 hybrid powder coating, because the resin components used are 50 / 50 polyester resin and E-12 epoxy resin, and the activity of E-12 epoxy resin is relatively high, while the common commercially available 50 / 50 polyester resin products are generally capped with trimellitic anhydride with high carboxyl activity, so that the final commercially available 50 / 50 ordinary polyester resin has high carboxyl activity and fast curing speed, resulting in gelation time of the coating film. Shorter, generally below 140s; and because the chain segment of polyester is relatively hard, it also leads to high softening point and high temperature viscosity, which makes the apparent leveling of the final coating film insufficient, orange peel is prone to appear, and the surface gloss of the coating film cannot be satisfied. People are satisfied, but it is very difficult to obtain high gloss (above 95%) for existing products and solutions

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